Abstract Reactive oxygen species (ROS), formed during redox fluctuations in iron-rich soils, have been known to stimulate lignin degradation, although not much is known about how they alter soil organic matter (SOM) composition and interaction with mineral surfaces. We conducted a laboratory experiment to see how ROS altered SOM composition and adsorptive fractionation onto Fe-mineral surfaces. We reacted water extracts of SOM with ·OH, produced by the Fenton reaction, and then conducted a sorption experiment of the extracts with goethite to analyze the amount and quality of SOM adsorbed. The Fenton reaction preferentially consumed low-O, mostly aromatic molecules, and new high-O molecules were detected post-Fenton, nearly half of which were carbohydrate-like. Although the amount of C adsorbed did not change after oxidation, the post-Fenton adsorbed molecules were more oxidized. Pre-Fenton adsorption was dominated by aromatic molecules (90%), but post-Fenton, the adsorbed molecules were 75% aromatic and 25% carbohydrate-like. We show that the ·OH radical oxidized SOM and shifted patterns of adsorption to a more oxidized pool. Because adsorption to minerals is thought to stabilize SOM, our results suggest that ROS may alter the availability and stabilization patterns of SOM.

中文翻译：

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活性氧改变土壤有机质的化学成分和吸附分馏

摘要 在富含铁的土壤中氧化还原波动期间形成的活性氧 (ROS) 已知会刺激木质素降解，尽管对它们如何改变土壤有机质 (SOM) 组成以及与矿物表面的相互作用知之甚少。我们进行了一项实验室实验，以了解 ROS 如何改变 SOM 组成和铁矿物表面的吸附分馏。我们将 SOM 的水提取物与 Fenton 反应产生的·OH 反应，然后用针铁矿对提取物进行吸附实验，以分析吸附的 SOM 的数量和质量。芬顿反应优先消耗低氧分子，主要是芳香族分子，芬顿后检测到新的高氧分子，其中近一半是类碳水化合物。虽然氧化后吸附的C量没有变化，芬顿吸附后的分子被更多地氧化。芬顿前的吸附主要是芳香族分子（90%），但芬顿后，吸附的分子是75%的芳香族和25%的类碳水化合物。我们表明·OH 自由基氧化了 SOM，并将吸附模式转移到更氧化的池中。因为对矿物质的吸附被认为可以稳定 SOM，我们的结果表明 ROS 可能会改变 SOM 的可用性和稳定模式。